Cast iron, ductile iron, copper, plastic (e.g. pvc), and steel pipes in all sizes are commonly employed in systems handling water, gas and other fluids at varying pressures. A difficult task in the construction industry is the passing of these pipes through a structural member such as a poured wall or floor (for example concrete) which are found in sewage or water treatment plants, and the like. Such concrete walls or floors vary in thickness and require many pipe penetrations. A wall penetration is any device which is fitted in a wall or floor to accept a pipe or conduit.
Presently, three commonly employed means, called wall penetrations, for passing a pipe through a concrete wall or floor include: wall castings (which are monolithically cast), wall pipes (which are fabricated), and wall sleeves. Positioning these wall penetrations and keeping them in position prior to and during the pouring of a wall is a difficult and important task. Wall castings or wall pipes are capable of being positioned prior to the pouring of a wall since they can be attached directly to concrete formwork. After the concrete wall has been poured and set, the concrete form work is removed, and continuing piping is attached to one or both sides of the wall casting or wall pipe.
A disadvantage of wall castings or wall pipes is that it is difficult to position them in such a way that they are normal to the wall. Continuing pipe is attached to both sides of the wall casting or wall pipe so if the wall penetration is not normal to the wall, problems are encountered due to the angles of departure of the continuing pipes from either side of the wall casting or wall pipe, i.e., they are not square with or normal to the wall.
A wall sleeve may also be placed in the formwork of a concrete wall prior to the pouring of the wall; however, a wall sleeve differs from a wall casting in that the carrying pipe passes through the wall sleeve coaxially. A disadvantage of a wall sleeve is that there is no stable means for the positioning wall sleeve on the concrete formwork prior to pouring the wall. An advantage, however, of the wall sleeve (over a wall pipe or wall casting) is that the problems discussed above with respect to the continuing pipe are eliminated since the carrying pipe passes coaxially through the wall sleeve. A wall sleeve has the flexibility to straighten out or realign the throughpipe.
There are three common types of joints or connections commonly employed with wall penetrations and these are: mechanical joint, push-on joint and flanged. The mechanical and push-on joints are not restrained connections and are generally used for underground pipes where at least some flexibility is required due to the earth's movement or the building settling. The flanged joint is a restrained joint which can be used when flexibility is not a requirement of the joint.
The mechanical joint consists of a bell, a mating pipe, a sealing gasket, a follower gland with bolt holes, bolts and nuts. The bell is provided with an exterior flange having bolt holes and a socket having annular recesses for the sealing gasket and the plain end of the pipe. The bell can be cast as an integral part of the pipe or connecting piece or may be cast as an integral part of the wall casting. The bell end of the pipe slips over the plain end of a mating pipe section. Thus, the connection is formed when the plain end of the pipe is actually inserted into the bell end of the pipe provided with the gasket. This type of connection is commonly referred to as a "stuffing box" connection. After insertion of the plain end of the pipe, gasket compression is achieved externally between the pipe bell and the mating pipe barrel with a mechanical joint gland. The mechanical joint is designed for pipes and fittings ranging from two to fifty-four inches.
The second type of connection is the push-on joint. The push-on joint is a single gasket joint wherein the pipe or fitting is forced into a bell containing a continuous, molded, annular gasket. The gasket is contained and forms a seal with the entering pipe or fitting. The difference between the push-on joint and the mechanical joint is that the gasket in a push-on joint is compressed as the beveled plain end of the mating pipe is inserted.
The third type of connection is flanged. A flanged connection is annular with studs or bolts attached thereto which allows a similarly flanged continuing pipe or fitting to be bolted to it. This type of fitting has virtually no flexibility and is mostly used inside plants, pumping stations or other structures.
There are several wall castings or wall sleeves which use the above described joints or connections. Wallace, in U.S. Pat. No. 4,071,265 issued Jan. 31, 1978, describes a threaded mechanical joint wall sleeve. The mechanical joint wall sleeve of Wallace comprises a cylindrical member and a pair of flanged end members or adapters. Each end member is adapted to receive a gasket which provides a seal with the carrying pipe which is inserted into the wall sleeve. The threaded mechanical joint wall sleeve of Wallace has to be threaded prior to its use on the field. Thus, pipe ends which are normally disposed of on the field cannot be used.
Davis, in U.S. Pat. No. 4,071,267, issued Jan. 31, 1978, describes a shrouded pipe wall casting for use with split-clamp couplings which is designed for use in concrete walls. The length of the wall casting is equal to the wall thickness and the ends are grooved for use with standard split clamp coupling. In the shrouded pipe wall casting of Davis, a water stop is integrally cast with the shroud which is welded to the pipe. Again, the grooved ends of the wall casting of Davis '267 are grooved prior to its use on the field.
Davis in U.S. Pat. No. 4,076,281, issued Feb. 28, 1978, describes a wall casting which is a threaded mechanical-joint bell fitting for use with cast iron pipe which passes through concrete walls. The mechanical-joint bell fitting of Davis is threaded so it can be screwed onto a threaded end of a carrying pipe section. The fitting comprises an integral bolting flange around the bell and optionally includes a circumferential water stop flange. Davis does not teach the attachment of the fitting directly to the concrete formwork but does teach the use of a support structure which is bolted to the concrete footings or slab.
Another type of wall penetration commonly employed is a wall sleeve which is provided with a ring of rubber-links which forms a seal between the wall sleeve and a carrying pipe which passes therethrough coaxially. The rubber-links are bolted together to form a seal which is a continuous circle.
When constructing large buildings such as sewage and water treatment plants, there have always been problems encountered when pipes pass through poured walls or floors, such as concrete walls or floors. First, a pressure differential builds up across a wall which may cause leakage problems after extended use. Second, the wall castings and wall pipes presently employed are difficult to obtain and very expensive since these wall penetrations have to be either monolithically cast or fabricated to a particular size depending on the thickness of the wall. Third, wall castings and wall pipes have to lie normal with the wall since continuing pipe is attached to the wall penetration. This can be a problem since it is very rare that a wall is poured perfectly even. Fourth, even though a wall sleeve is more flexible than a wall casting or wall pipe, it is very difficult to position wall sleeves on the formwork prior to the pouring of a wall.
Means for penetrating a poured wall or floor is needed which counteracts a pressure differential across a wall, is easily and inexpensively obtained, is capable of being positioned on formwork with accuracy without a tendency towards slippage, and does not have to lie perfectly flush with a poured wall.